Technical data
Gateway Routing Daemon (GATED) Configuration Reference
A.18 Control Statements
An
origin
of
igp
indicates the route was learned from an intradomain routing
protocol and is most likely complete. An origin of
egp
indicates the route was
learned from an interdomain routing protocol that does not support AS paths
(EGP, for example), and the path is most likely not complete. When the path
information is definitely not complete, an origin of
incomplete
is used. An origin
of
any
can be used for any origin.
A.18.2.2 AS Path Regular Expressions
Technically, an AS path regular expression is a regular expression with the
alphabet being the set of AS numbers. An AS path regular expression is
composed of one or more AS paths expressions. An AS path expressions is
composed of AS path terms and AS path operators.
A.18.2.3 AS Path Terms
An AS path term is one of the following three objects:
• autonomous_system
Specifies any valid autonomous system number, from one through 65534
inclusive.
• dot (.)
Matches any autonomous system number.
•
( aspath_regexp )
Group subexpressions in parenthese. An operator, such as * or ? works on a
single element or on a regular expression enclosed in parentheses.
A.18.2.4 AS Path Operators
An AS path operator is one of the following:
• aspath_term {m,n}
Indicates a regular expression followed by {m,n} (where m and n are
nonnegative integers and m <= n) specifies at least m and at most n
repetitions.
• aspath_term {m}
Indicates a regular expression followed by {m}. When m is a positive integer,
the expression specifies exactly m repetitions.
• aspath_term {m,}
Indicates a regular expression followed by {m,} (where m is a positive integer),
and specifies m or more repetitions.
• aspath_term *
Indicates an AS path term followed by asterisk (*), specifying zero or more
repetitions. This is shorthand for {0,}.
• aspath_term +
Indicates a regular expression followed by plus sign (+), specifying one or
more repetitions. This is shorthand for {1,}.
• aspath_term ?
Indicates a regular expression followed by question mark (?), specifying zero
or one repetition. This is shorthand for {0,1}.
A–34 Gateway Routing Daemon (GATED) Configuration Reference